Hu ZhangState Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Key Laboratory of Environment and Control for Flight Vehicle, School of Aerospace, Xi'an Jiaotong University, Xi'an, 710049,
China

Yueming LiState Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Key Laboratory of
Environment and Control for Flight Vehicle, School of Aerospace, Xi'an Jiaotong University, Xi'an, 710049,
China

Wen-Quan TaoKey Laboratory of Thermo-Fluid Science and Engineering of MOE, School of Energy and Power
Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China

摘要

Aerogels have extremely low density, high porosity and superior insulation performance; therefore they have
widespread application value and prospect. But they are semi-transparent for thermal radiation at high
temperature. Thermal conductivity measurement is an important way of evaluating their thermal insulation
performance. The theoretical basis of transient plane source method is based on unsteady differential equation of
conduction which is suitable for opaque medium. For semi-transparent materials, radiation will participate in the
thermal transport process. The existence of thermal radiation within the materials will affect the test accuracy. In
present study, the effect of radiative heat transfer on determining thermal conductivity of semi-transparent
materials using transient plane source method is numerically studied. Semi-transparent materials with different
extinction coefficient are studied at different temperature by simulating 1 dimensional steady heat transfer
process the same as the experiment of steady method. The calculated thermal conductivity is selected as
reference for comparison with transient plane source method. The heat transfer process of applying transient
plane source method to semi-transparent materials is mimicked numerically as experimental test of transient
plane source method. The results show that the thermal conductivity of semi-transparent materials measured
by transient plane source method will be overestimated at temperature higher than 600 K and extinction
coefficient less than 2000 m-1 where radiative heat transfer is dominant. The deviation increases with
temperature and reaches to 19.6% at 1000 K and 500 m-1. It illustrates that radiative heat transfer will affect
the thermal conductivity accuracy of semi-transparent materials.